Online learning has become an integral part of students' learning, and the development of internet-specific epistemic justification (ISEJ) has considerable significance in promoting learners' online learning effectiveness. This study aimed to explore the roles of college students' grades, learning media preference, online learning engagement (OLE), achievement goals (AG), and internet-based learning self-efficacy (IBLSE) on the ISEJ (personal justification, justification by multiple sources, and justification by authority) to propose effective ways to foster ISEJ. The study investigated 406 college students and found that undergraduate students are more engaged in online learning than graduate students and have higher levels of performance-approach goals. In addition, students who prefer to learn through papers and online resources have more sophisticated justification by multiple sources than those who prefer papers and also have higher levels of performance-avoidance goals than those who prefer online learning. Further, OLE, AG, and IBLSE can jointly predict the three dimensions of ISEJ. Among them, the mastery-approach goal is a common positive predictor for all three dimensions. Finally, IBLSE can moderate the relationship between behavioral engagement and personal justification.